This study will use the two most widespread and comprehensive sources of nonfatal occupational injury and illness reporting to evaluate the completeness of reporting and factors that affect differential reporting. These sources are state workers' compensation data and the Survey of Occupational Injuries and Illnesses conducted annually by the Bureau of Labor Statistics. It also will provide improved estimates of the overall annual incidence of occupational injuries and illnesses for 8 states: Oregon, Washington, Wisconsin, New Mexico, Florida, Texas, Minnesota, and West Virginia. In addition, it will develop and evaluate methods for matching occupational injury and illness data from multiple sources. Finally, it will apply capture-recapture analysis with capture rates that vary by individual, employer, and injury characteristics. This will allow us to determine how reporting rates differ by these characteristics. For 1998-2000, the study will compare reported injuries from these two sources by matching individual injuries and illnesses in 8 states. It will develop methods for matching data from the two sources and for estimating the proportion of records falsely matched. It then will use capture-recapture analysis for each of these states to develop improved measures of nonfatal injury incidence. The study will use logistic regression to account for differential capture by employer, injury, and worker characteristics. This also will enable us to identify factors associated with underreporting. Then, we will compare the degree to which the two data systems appear to capture occupational injuries and illnesses in the states studied. The study will provide improved estimates of incidence and underreporting in each study state for injuries that involve days away from work and which are reported to state workers' compensation systems. For 4 of the 8 states, the estimates will cover all injuries involving at least one day off work. For all 8 states, the study will generate comparable estimates for injuries involving at least 8 days off work. If, contingent on covariates, capture is uniform across states, capture rates estimated from the studied states will be applied to states outside the study population to provide improved national estimates of the incidence of injuries and illnesses.